In order to optimise production in a well, it is important to know the characteristics of the well fluid, such as the density, the amount of particles and gas/water bubbles, the temperature and the velocity.
Velocity measurements can be performed in different ways. One way is to measure the capacitance between two pairs of electrodes, and by comparing the measurements conducted in the two pairs, the velocity of the fluid can be calculated. However, such measurements are based on a presumption that the fluid is distributed evenly, which is not always the case. Another way to measure velocity is to use tracers in the fluid, which contaminates the fluid.